I often see "glitches" when using the keyboard shortcuts to skip backward or forward while watching a video. I believe it's only happened while watching a file which is still being recorded. I'm recording TV using Hauppauge WinTV v10 (on Windows 11), which creates files with a .TS extension. VLC will play the beginning of these while more video is being added to the end of the file. The timeline initially reflects the amount of video when VLS starts playing, but the end time point will move out as the player gets to the end (by playing or forward skip). But sometimes, instead of a 10s jump (forward or backward), the time point jumps ahead several minutes (or, I think, sometimes backward). I believe I've seen a back skip (Left Arrow) jump forward by a big chunk, and I believe I've seen a skip forward (Right Arrow) sometimes jump back a big chunk.
I'm not 100% sure, but I think this happens mostly when the current play time point is close to the original (and displayed) end point, even if the file has accumulated a lot more time since beginning play. When just playing forward past the original end point (and extending it as it goes) nothing odd happens. But when I try a skip (over commercials or between plays in a football game) I sometimes see the behavior. I should also mention that I'm almost always playing at a speed other than 1.0; I typically use 1.2 for most regular programs and 1.7 for sports (and a few other) programs.